Keyboard for the control box of an electric apparatus

ABSTRACT

Keyboard for the control box (11) of an electric apparatus comprising a sheet (1) which forms a plurality of contactors (2) each projecting from the sheet through a blister (3) which is elastically deformable and which acts as a spring, the contactors (2) being provided with bearing keys (8) and contact pads (5) intended to come into contact with a printed circuit (12) arranged under the sheet (1) of contactors when a pressure is exerted on the keys. This keyboard is remarkable in that at least certain of the contactors (2) are provided with stubs (4) arranged opposite the contact pads (5) and which are intended to be force fitted into corresponding housings provided in the bearing keys (8).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a keyboard for a control box of an electricapparatus.

2. Description of Pertinent Information

Traditional keyboards for control boxes of electrical apparatuses suchas calculators and telephones generally comprise plastic bearing keysprovided with metallic contact pads which act on a printed circuit.

The keys of these traditional keyboards are biased in their restingposition out of contact with the printed circuit by springs.

As these keyboards evolved, the springs were eliminated by using a sheetof contactors made of non-conducting silicone, each contactor projectingfrom the sheet through a blister forming a spring. The metallic padswere then advantageously replaced with pads made of conducting silicone.

In these apparatuses, the plastic keys are guided by and rest upon thecontactors.

Other types of keyboards were also developed in which the keys aredirectly molded with the sheet of contactors. In these keyboards thekeys are also made of silicone.

Both types of keyboards suffer from disadvantages. One of thedisadvantages of the apparatuses in which the keys are separate from thesheet of contactors, resides in the need and difficulty in assemblingthese separate elements in the box, whereas the keyboards are generallymade and delivered separately.

The apparatuses in which the silicone keys are integrally formed withthe sheet of contactors have, on the other hand, the disadvantage ofreducing disposable space under the sheet.

If to remedy this situation, the interior of the keys are hollowed outto gain space, they then risk not being sufficiently rigid, particularlywhen the keys are provided with several contact pads.

Finally, it is impossible, with both types of keyboards, to light thekeyboard with luminescent diodes without resorting to complicated orcumbersome apparatuses using double printed circuits, for example.

SUMMARY OF THE INVENTION

It is an object of the present invention to solve these problems byseparating the bearing keys from the sheet of contactors but in anoriginal way so as to produce a complete keyboard ready for use.

The keyboard according to the invention comprises a sheet which forms aplurality of contactors each projecting from the sheet by means of ablister which is elastically deformable and which acts as a spring. Thecontactors are also provided with bearing keys and contact pads adaptedto come into contact with a printed circuit, arranged under the sheet ofcontactors, when a pressure is exerted on the keys. This keyboard isremarkable in that at least some of the contactors have stubs arrangedopposite from the contact pads which are adapted to be force nested intocorresponding housings provided in the bearing keys.

Advantageously, for reasons which will be seen later, the sheet ofcontactors has projections adapted to rest on the printed circuit insuch a manner to create a space between the latter and the sheet ofcontactors.

In this case, the projections are preferably arranged arounddisplacement axes of the contact pads.

In the embodiment using the separation projections mentioned earlier,the sheet of contactors is traversed by one or several luminescentdiodes positioned between the contactors and under or between the keyswhile the sheet of contactors and the keys have a free space betweenthem and the box in such a manner so as to permit the light of thediodes to be diffused in this space after having been diffused in thespace between the printed circuit and the sheet of contactors.

It is within the scope of the invention for the bearing keys to beformed individually or together in any material such as plastic, or anyother material.

According to a particularly interesting embodiment the bearing keys areformed from a block in a sheet of keys which covers the sheet ofcontactors. In this embodiment each key projects from the sheet of keysby means of a supple blister which covers one or several of theelastically deformable blisters of the sheet of contactors.

The sheet of contactors and the sheet of keys are preferably composed ofnon-conducting silicone whereas the contact pads are composed ofconducting silicone.

In the embodiment in which certain keys control several contactors, itcan be advantageous for at least some of these keys to each have atleast one perforation arranged in the corresponding supple blister ofthe key so as to allow diffusion of light through this perforation fromat least one diode which traverses the sheet of contactors and which ispositioned under the key and between the contactors of the latter.

When the keys are formed from a supple material, such as silicone, atleast some of these keys can be rendered rigid by plastic reinforcementswhich are nested in the same stubs of the sheet of contactors as thekeys.

Finally, the invention also proposes a procedure for manufacturing akeyboard whose keys are all integral with the same sheet, as mentionedearlier, which is remarkable in that the sheet of contactors is made bymolding such that at least some are provided with stubs and the sheet ofbearing keys is provided with housings corresponding to the stubs. Themethod further comprises the step of superposing the two sheets andnesting the stubs of the sheet of contactors by pressure in thecorresponding housings of the sheet of keys.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and its advantages will be clearly understood upon readingthe detailed description which follows of an embodiment according to theinvention in in conjunction with the attached drawings in which:

FIG. 1 illustrates a plan view of a sheet of contactors according to theinvention;

FIGS. 2 and 3 illustrate cross-sectional views taken, respectively,along lines II--II and III--III of FIG. 1;

FIG. 4 illustrates a plan view of a sheet of bearing keys according tothe invention;

FIGS. 5 and 6 illustrate cross-sectional views taken, respectively, aresections along lines V--V and VI--VI of FIG. 4,

FIG. 7 illustrates a plan view of a control box provided with a keyboardaccording to the invention;

FIGS. 8 and 9 illustrate cross-sectional views taken, respectively,along lines VIII--VIII and IX--IX of FIG. 7.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

FIGS. 1, 2 and 3 illustrate a sheet 1 obtained by molding non-conductingsilicone comprising a plurality of contactors 2.

Each contactor 2 projects from the sheet 1 through a blister 3 which issupple. Blister 3 elastically deformable and comprises a stub 4 and acontact pad 5 positioned on the opposite which is arranged in theblister 3. Contact pad 5 is made of conducting silicone, for example.

Coaxial to the axes of stubs 4 and pads 5, sheet 1 has annularprojections 6 whose function will be discussed later.

FIGS. 4, 5 and 6 illustrate a sheet 7 also formed by molding of siliconeand which comprises a plurality of bearing keys 8.

The keys 8 have different lengths and project from the sheet 7 throughblisters 9. The inside of keys 8 are provided with at least one housing10 in a shape corresponding to that of the stubs 4 of the contactors 2.Blisters 9 include an oblique portion 9', which corresponds to anoblique portion 3' of blister 3 of sheet 1.

FIGS. 7, 8 and 9 illustrate a control box 11 in which the keyboard ofthe invention is mounted.

In box 11 a printed circuit 12 is positioned in a traditional manner andis provided with electronic components 13, 13'.

As more specifically illustrated in FIGS. 8 and 9, sheet 1 of contactorsand sheet 7 of keys are integrally attached by force fitting of stubs 4of the contactors in housings 10 of the keys.

The two integral sheets 1 and 7 rest on printed circuit 12 byprojections 6 in such a manner that there exists a space between printedcircuit 12 and the sheets.

The Figures also permit one to understand the simple manufacturingprocedure of the present invention.

The process comprises the steps of producing by molding, sheets 1 and 7illustrated in the figures, superimposing the sheets and integrallyattaching the sheets as illustrated in FIGS. 8 and 9.

It is clear that the adjustment and arrangement of the contactors andthe keys are positioned so that the stubs 4 of the contactors face thehousings 10 of the keys.

It is important to note that if blisters 3 of the contactors 2 act as aspring so as to cause the contactors to return to their initial positionafter depression of the keys, the blisters 9 are simply supple andadapted to allow the sheet of keys to deform itself so that the keysaccompany the contactors. During operation, when a pressure is appliedon the keys, contact pad 5 contacts a corresponding portion 5' of theprinted circuit board.

As illustrated in FIGS. 8 and 9, luminescent diodes 14 and 14' arearranged in the printed circuit 12 and traverse the perforations 15, 15'provided in the sheet 1 of the contactors.

In this embodiment, the diodes 14 and 14' are provided under the longkeys with several contactors and such that the diodes are positionedbetween the contactors 2 of the key.

These keys have on the large sides of their blisters 9 perforations ascan be seen at reference numeral 16 of FIGS. 6 and 9.

As illustrated in FIGS. 8 and 9 sheets 1 and 7 have peripheral edgeswhich are positioned at a distance from box 11.

Moreover, a small translucent plate 17, illustrated in FIGS. 8 and 9, isfitted in box 11.

The small plate 17 has perforations corresponding to keys 8 whichtraverse the perforations. As illustrated in FIGS. 7-9 this small plate19 rests on an edge 18 of the box and shoulders of the keys abut on thesmall plate.

As also illustrated in FIGS. 8 and 9, reinforcements such as inserts 19and 19' made of polyamide for example, are provided for at least thekeys controlling several contactors.

The reinforcements 19 and 19' have perforations adapted to be traversedby the stubs 4 of the contactors 2 of the relevant keys and can also beprovided with a groove 20, 20' to accommodate diodes 14, 14' when thesekeys are pressed.

It is clear that with such an embodiment the light emitted from diodes14, 14' can be diffused under the keys, between the contactors 2 andthrough the perforations 16 of the blisters 9. Moreover, the light canalso be diffused over the entire keyboard by means of the space betweenthe sheet 1 and the printed circuit 12, and the space between the sheets1, 7 and the box 11.

The invention is not limited to the embodiment described above.

Thus, it is within the scope of the invention for keys 8 not to be apart of the sheet 7 but to be individually arranged.

Further, although projections 6 allow a diffusion of the light of thediodes 14, 14', the latter are not compulsory.

The diodes can, moreover, be positioned under the simple keys, in whichcase sheet 1 and the keys can be transluscent, or the diodes can even bepositioned between two keys.

In addition, reinforcement 19, 19' can also be provided for simple keys.

Also, the keys with several contactors can simply rest upon certaincontactors among them, the latter then not having stubs 4.

Finally, the keyboard shown in FIGS. 7-9 is given by way of example andnumerous arrangements can be conceived within the scope of theinvention, such as their use in calculators and telephones.

I claim:
 1. A keyboard for a control box of an electrical apparatuscomprising:(a) a first sheet comprising:(i) a plurality of contactors,wherein each of said contactors comprises an elastically deformableblister projecting from said first sheet to function as a spring; and(ii) a plurality of contact pads positioned within said blisters; and(b) a second sheet comprising a plurality of keys, each having a housingtherein, wherein said plurality of contact pads comprise means forcontacting a printed circuit in response to a pressure applied on saidplurality of keys, wherein at least one of said plurality of contactorscomprises a stub positioned atop of said contactor opposite from saidcontact pads, and wherein said at least one stub comprises means forbeing force fitted into said housing of one of said plurality of keys.2. The keyboard defined by claim 1, wherein said printed circuit ismounted on a printed circuit board.
 3. The keyboard defined by claim 2,wherein said first sheet further comprises a plurality of projectionseach comprising means for contacting said printed circuit board andspacing said contactors from said printed circuit.
 4. The keyboarddefined by claim 3, wherein each of said contact pads is adapted to bedisplaced along a displacement axis, wherein said projections arecoaxially positioned to said contact pads.
 5. The keyboard defined byclaim 3, wherein said first sheet and said second sheet are spaced fromthe edges of a control box, wherein said printed circuit board comprisesat least one luminescent diode positioned thereon within said controlbox such that the light emitted by said at least one diode firsttraverses the space between said printed circuit board and saidcontactors, and then traverses the space defined by oblique portions ofsaid first and second sheets, and the space defined by said plurality ofkeys and said edges of said control box.
 6. The keyboard defined byclaim 5 wherein said at least one diode is positioned between saidcontactors.
 7. The keyboard defined by claim 5 wherein said at least onediode is positioned between said keys.
 8. The keyboard defined by claim5 further comprising a plurality of luminescent diodes.
 9. The keyboarddefined by claim 5, wherein said at least one diode extends through aperforation in said first sheet.
 10. The keyboard defined by claim 1,wherein said second sheet covers said first sheet, wherein each keycomprises a supple blister projecting from said second sheet, wherein atleast one supple blister covers at least one elastically deformableblister of said first sheet.
 11. The keyboard defined by claim 10wherein said at least one supple blister covers a plurality ofelastically deformable blisters on said first sheet.
 12. The keyboarddefined by claim 10, wherein each of said first and second sheets isformed of a non-conducting silicone, and each of said contact pads isformed of a conducting silicone.
 13. The keyboard defined by claim 4,wherein at least one key controls a plurality of contactors, wherein atleast one of said keys comprises a perforation therein arranged on asupple blister corresponding to said at least one of said keys.
 14. Thekeyboard defined by claim 13, wherein said perforation is positioned soas to permit light to pass therethrough from a luminescent diodeextending through said first sheet and positioned on a printed circuitboard under said at least one key and between said plurality ofcontactors controlled by said at least one key.
 15. The keyboard definedby claim 1 further comprising a translucent plate having a plurality ofperforations therein through which said plurality of keys extend. 16.The keyboard defined by claim 1, wherein each said first sheet and saidsecond sheet are made of a supple material, wherein at least one of saidplurality of keys comprises at least one plastic reinforcementpositioned in said housing of said at least one plurality of keys. 17.The keyboard defined by claim 16, wherein each of said keys comprisessaid at least one plastic reinforcement.
 18. The keyboard defined byclaim 16 wherein said at least one plurality of keys comprises aplurality of plastic reinforcements.